well... let me think outloud here.
these are the basic four once you have your initial stuff (mask, fins, weights)
1. bouyancy device
2. reg/octo
3. pressure gage/depthgage/computer
4. exposure protection
if at all possible, i would reccomend that you buy them together, that way you
will be in your own gear, will grow used to it, and thus be safer overall and
have more fun
i would rather rent 3 and 4 and buy 1 and 2 first. but that's because i'm an average-
built Florida diver and don't mind diving without a computer (i.e. exposure protection
is not a big issue for me and a stock wetsuit fits me fine, and i don't mind using
tables)
on the other hand, i would feel too uncomfortable switching BC's and regs,
and getting used to how different regs breathe, and how much and where the
bouyancy is with the various BC's, etc...
i think this is a decision you are going to make based on your priorities and comfort level